1. Field of the Invention
The present invention relates to umbrellas, and more particularly to an umbrella that is resistant to inversion from the wind.
2. Description of Related Art
Frequently, a wind will catch an umbrella user unaware and exert a force against the inner surface of the canopy which will cause the canopy to invert from its normal operable position to an upwardly convex position. Accordingly, specially designed umbrellas for rainy, windy weather have been proposed.
As shown in FIGS. 1 and 2, this disclosed windproof umbrella C has an upper canopy C2 in covering relation to a lower canopy C1 in which the canopy C1 has a plurality of (e.g., eight) vent holes H each correspondingly arranged in a sector C3. The upper canopy C2 is disposed over the vent holes H. The area of the upper canopy C2 is about three fifth of the area of the lower canopy C1. In order to secure the bottom edge of the upper canopy C2 to the umbrella C, eight elastic strips E are provided, wherein each of the elastic strips E with one end sewn to a corner of adjacent sectors C4 of the upper canopy C2, and the opposite end fitted tightly onto a tip of a rib G. During rainy, windy weather, wind I that is caught beneath the lower canopy C1 exit through the vent holes H and applies pressure to the underside of the upper canopy C2. This forces the upper canopy C2 lift away from the lower canopy C1 by means of the elastic strips E which are stretched to provide a path for wind I to escape the umbrella C. However, because the elastic strips E often stretched, its elasticity will be worn out after used for a predetermined times. As a result, the escape space for wind I will become larger.
Thus, heavy rain may enter the space between the lower canopy sectors C3 and the upper canopy sectors C4 and fall through bottom edges H1 of the vent holes H in the lower canopy C1 onto the user. Further, the manufacturing process of the windproof umbrella C is time consuming. For example, the upper canopy C2 comprises eight sectors C4. Two edges of each canopy sector C4 are secured to the ribs G by means of stitching respectively. As stated above, the corner of adjacent canopy sectors C4 is sewn to one end of the elastic strip E, and the opposite end of the elastic strip E is fitted tightly onto the tip of the rib G. Furthermore, the lower canopy C1 and the upper canopy C2 (via the stretched elastic strips E) both exert a force onto the tip of the rib G and thus, the elastic strips E are very taut. As a result, the elastic strips E are prone to be separated from the tips of the ribs G in case of the tip of the ribs G damaged. Once the elastic strips E are separated from the tips of the ribs G, upper canopy C2 will be lifted by the upward wind I caught beneath the canopy C1. Thus, the windproof function of the umbrella C will be completely worthless because the bottom edges H1 of the vent holes H are not covered anymore.
An umbrella C which is similar in construction is disclosed in FIGS. 3 and 4. A circular vent hole H is provided in the center portion of a canopy C1. A small circular piece of fabric C2 is positioned over the canopy C1 in covering relation to the vent hole H. The area of the piece of fabric C2 is about two fifth of the area of the canopy C1. Accordingly, an elastic strip E, which attached from a corner of adjacent fabric sectors C3 to a tip G, will have a relatively longer length as compared with the elastic strip E illustrated in FIGS. 1 and 2. Further, because the price of elastic strip is higher than that of fabric, the cost of manufacturing the umbrella shown in FIGS. 3 and 4 will be higher than that of FIGS. 1 and 2 in spite of the saving in fabric. Furthermore, the umbrella of FIGS. 3 and 4 has the same disadvantage as that of FIGS. 1 and 2 in respect of the elastic fatigue of the elastic strips.
Thus, it is desirable to provide a windproof umbrella to overcome the above drawbacks of prior art.